1. Field of the Invention
The subject invention generally pertains to centrifugal blowers and more specifically to an inlet flow distributor for such a blower.
2. Description of Related Art
Centrifugal fans and blowers usually have a fan wheel that draws air in a direction generally parallel to the fan wheel's rotational axis and discharges the air in a tangential or radial direction that is normally perpendicular to the axis. In cases where the blower is installed inside an enclosure, the blower's inlet may face a side wall of the enclosure. If that side wall is too close to the inlet, the wall can disturb an otherwise uniform airflow pattern into the blower's inlet. Such a disruption can create undesirable swirling of the air and reduce the fan's performance.
Although it appears that little if any effort has been applied to addressing the problem of a blower's inlet being too close to an adjacent wall, some blowers have inlet flow directors for dealing with other problems associated with centrifugal blowers. Examples of such deflectors are disclosed in Japanese Patent Application 59-196997 and U.S. Pat. Nos. 5,570,996; 4,549,848; 820,399; and 820,398. In each of these examples, the deflector is somewhat of a funnel with an inner surface that channels the airflow in a desired direction.
In the '398, '399, and '848 patents, it appears that the fan housing needs to be enlarged to accommodate the added deflector. Enlarging the housing can increase its cost and perhaps decrease the blower's efficiency. Moreover, the '398 patent shows significant swirling, mixing, and recirculation of the air.
The blower of the '996 patent does require a larger fan housing; however, the deflector extends a significant distance into the housing and actually obstructs a portion of the fan wheel. Although the deflector of the '996 may have an overall positive effect on the blower's efficiency, some loss may still occur where the deflector directly obstructs the fan wheel. The Japanese reference shows a deflector that not only extends into the fan wheel but also chokes off about half of the fan's inlet.
None of the aforementioned references show a blower with an inlet facing an adjacent wall. U.S. Pat. Nos. 6,027,406; 4,295,416 and 4,319,521, however, show inlet silencers that help guide suction air into a blower. Each of the silencers appears to be a symmetrical body that receives airflow from multiple radial directions and redirects the airflow upward into an inlet opening of the blower. It does not appear that the inlet silencers correct any non-uniform incoming airflow pattern.
Consequently, a need still exists for an inlet flow distributor that corrects the non-uniform airflow pattern created by a wall in proximity to a fan inlet.